Why do I see peaks in the graphs of the SDR software (especially in the oxygen signal) when I open the incubator door / take the plates out of the incubator?

There are different reasons:

Temperature effect: The signal of the optical sensor, especially the oxygen sensor, depends on temperature. If you open the incubator, the temperature changes, but the software uses the constant, user-defined temperature typed into the software for calculation. A temperature drop leads to decreasing oxygen / pH signals and vice versa.

OxoDish® & hypoxic conditions: Opening of the incubator door leads to an upward peak in oxygen because ambient air enters the hypoxic sample.

HydroDish® & CO2 atmosphere: Opening the incubator door leads to an upward peak because CO2 leaves the incubator. As the pH of the buffer for cell cultivation is regulated by the CO2 atmosphere in the incubator, this leads to a higher pH within the sample.